Binary flip-flop element for pneumatic digital computer



Feb. 9, SAMET BINARY FLIP-FLOP ELEMENT FOR PNEUMATIC DIGITAL COMPUTER Filed June 4, 1962 TO OUTPUT I TO OUTPUT I1 TO OUTPUT II FIG. 2

FRANK SAMET INVENTOR.

BY W

ATTORNEYS United States Patent 0 3,168,898 BINARY FLIP-FLOP ELEMENT FOR PNEUMATIC DIGITAL COMPUTER Frank Samet, New York, N.Y., assignor to General Precision Inc., Little Falls, N.J., a corporation of Delaware Filed June 4, 1962, Ser. No. 199,671 6 Claims. (Cl. 137-119) This invention relates to pneumatic digital computer elements and circuits used in conjunction therewith, and is particularly directed to a digital computer element which is used as a binary flip-flop.

The primary feature of the invention is that a single bistable element actuated by negative pulses or openings is utilized as a flip-flop.

This invention represents an improvement on a copending application, Serial No. 113,911, now abandoned, filed in the United States Patent Oflice on the 31st day of May 1961, by Hugh E. Riordan, directed to a Pneumatic Computer Element, and assigned to the same assignee as the present invention.

This invention is directed primarily to computer elements used in hot gas systems, in which gas at high temperatures and relatively high pressures is utilized.

A primary feature of the construction is that the computer element is relatively small, compact, and in which the fit between the ball or piston and the cylinder in which it is reciprocatively mounted, while fairly close, still provides some clearance so that a certain amount of leakage is provided past the piston or reciprocative ball within the cylinder in which the ball or piston is operated.

In general, most digital computer functions can be performed by circuits employing appropriate combinations of binary flip-flops and other elements.

A flip-flop element such as that provided by applicant has the property of changing its state, and hence its polarity or the level of its output upon successive application of input signals. In this manner, the flip-flop element can perform a wide range of digital computer operations, such as counting, switching, and memory. I g

In applicants flip-flop element, input signals are supplied by negative pulses or momentary input lead openings. 2

Another feature is that the operation of the computer element is controlled by negative pulses or by openings in combination with restricted passages or orifices through the system.

Another object of the present invention is the provision of a pneumatic computer element applicable for use in a hot gas operated guidance and control system requiring high temperature capabilities and having high response speed and accuracy requirements.

Another object is to provide a pneumatic computer element and a circuit used in conjunction therewith, which are capable of performing basic digital functions.

A further object of the invention is the provision of a pneumatic computer element and a circuit therefor, the computer element having a number of operational stable positions enabling the device to perform a wide range of digital computation functions.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

In the drawings:

FIGURE 1 is a schematic longitudinal sectional view through a preferred embodiment of the bistable element, and the circuit used in conjunction therewith, including a plurality of restriction orifices, connected to the element.

3,168,8fi3 Patented Feb. 9, 1965 FIGURE 2 is a schematic longitudinal section, similar to FIGURE 1, through a portion of the computer element shown in FIGURE 1, showing the ball transferred to the second stable position.

It will be understood that the following description of the construction and the method of connection, con trol, operation, and utilization of the pneumatic computer element and circuit therefor is intended as explanatory of the invention and not restrictive thereof.

In the drawings, the same reference numerals designate the same parts throughout the various views, except where otherwise indicated.

One embodiment of the gas-controlled computer element shown in FIGURE 1 comprises enclosure means such as a body 10, having a substantially cylindrical cavity 11 formed in the interior thereof, and a valve member taking the form of a spherical ball 12 slidably fitted to the cavity 11.

The body 10 of the computer element has four tubular connections formed therein, including two axial passages or connections 14, 15, each of which has an integral ball seat 17, 18 formed therein, the ball seats protruding into the central cavity, and two side passages 20, 21, one of which is located near one of the axial passages 14, 15, the other being located near the second axial passage 15. The side passages 20, 21 are located near the ball seats 17, 18 of the axially aligned passages 14, 15.

Each of the side passages 20, 21 is open to the atmosphere through the flow restrictions 27 and 28, which are inserted in each of the side passages 20, 21.

Since the ball 12 is not tightly fitted to the cavity 11, a small predetermined portion of the gas flowing through the axial passage 15, passes through the cavity 11, around the ball 12 and out through the side passage 20, in the ball position shown in FIGURE 1.

The two stable positions of the ball, adjacent the ball seats 17, 18 are designated A and B, in FIGURES l and 2, each representing the position of the ball when in contact with one of the ball seats. A suitable gas supply is provided at P the gas flowing through a pair of lines 23, 24, each' of which has a suitably designed fiow re strictive orifice 25,26 therein leading to the two axially aligned connections 14, 15 in the body of the element. 7 P designates the gas pressure at one of the axially aligned connections 14 and P the gas pressure at the second axially aligned connection 15 and in the adjacent cylinder cavity 11.

P designates the gas pressure against the ball surface within a portion 11a of the cylindrical cavity 11, between the outer circumference of the ball seat, and the v inner circumference of the upper portion of the cavity.

The pressure in the portion of the cavity 11, below the ball is greater than that in the portion 11a above the ball 12. In stable position A, the ball is seated against the seat 17 terminating the axial connection 14. In the position B, shown in FIGURE 2, the ball is seated on the seat 18 terminating the second axial connection 15.

The leads 23, 24 are connected to leads 30, 31, respectively, each of which has a restriction 32, 33 inserted therein, the two leads 30, 31 merging into outlet line 34 which is open to the atmosphere, through an outlet flow restriction 36 which is incorporated therein.

' A line 37 is connected from the input signal source to the line 34 on the upstream side of restriction 36 and is normally closed.

Output sensing devices or subsequent computer stages are connected to the portion of the circuit designated Output I which is located between the two restrictive orifices 25 and 32, and to the other portion of the circuit designated Output II which is located between the two restrictive orifices 26 and 33, in the opposite half of the element, respectively. Pressure differentials occur at these output positions as a result of input signals as will hereinafter be described in greater detail.

The body iii of the element is generally symmetrical about the horizontal axis 38 shown in FIGURE 1, so that the length and cross-section of the leads, and the diameter and length of the restrictive orifices located above and below the axis are substantially identical.

Thus axial connections 14 and are equal in diameter and length.

This also applies to the restrictive orifices and 26, incorporated in the lines 23, 24.

The dimensions of some of the restrictive orifices such as 25, 26, 32, and 33 are determined with consideration for the fact that when critical flow occurs through an orifice (i.e., when flow velocity of the gas is at or above the speed of sound transmission in the gas) pressure fluctuations occurring downstream of the orifice cannot be propagated in an upstream direction through the orifice. Critical flow occurs when the ratio of pressure on the downstream side of the orifice to pressure on the up stream side is below a critical value K which is a characteristic of a gas (e.g., K=0.53 for air). The propagation of pressure fluctuations in a downstream direction is independent of whether the flow through the orifice is critical or subcritieal.

In the construction shown in FIGURES l and 2, re-

strictions 25 and 26 in the gas supply lines, and outlet FIGURE 1, the upward forces exerted on the ball by the gas pressure in the lower portion of the cavity 11 must be greater than the downward forces exerted by the combined pressures P acting on the spherical segmental area of the ball in contact with P and pressure P in the upper portion 11 of the cylindrical cavity acting on the remaining portion of the hemispherical segment of the ball, beyond the seat, in contact with P If M is the area of the projection of the ball, and N the area of the projection of the spherical segment in contact with P the condition illustrated by FIGURE 1 is maintained, when (1) 2M l N 3(MN 1 The actual area of the circumferential seat 17 and the weight of the ball both of which are relatively small, have been neglected in the above equation.

- It can be seen from the above equation, that if a substantial drop occurs in the pressure P in the lower portion of the cavity'll, while the upper pressures P and P remain substantially constant, the direction of the pressure differential maintaining the ball in position A, shown in FIGURE 1, would be reversed and the balllZ would be moved downward against the seat 18 into the position shown in FIGURE 2, thus reversing the state of the element.

' Flow and pressure conditions in the element condition shown in FIGURE 1, before a subsequent control signal is applied, are as follows:

P the pressure at the axial connection 14 between the restrictions 25 and 32 is smaller than 0.531 because the restriction orifice 25 is critical at all times.

P the pressure in the section of the circuit between the three right-hand restrictions 32, 33, and 36, is smaller than O;53P and therefore orifice 32 is critical under the stated conditions.

P P because in addition to the gas flow through restriction orifices 33 and 36, which is equivalent to 32 and 36, the fluid passing through the axial connection 15 has a two additional outlets. These include side outlet 21 which is open to the atmosphere, and the upper side outlet 20, which the fluid reaches after it passes the restriction between the ball 12 and the inner surface of the cavity 11.

P can be made sufiiciently low, compared to P so that the ratio P /P and the restriction orifice 33 are no longer critical. In this way pressure fluctuations beyond restriction orifice 33 will be propagated back to P through axial connection 15.

P P in the state illustrated in FIGURE 1, with the ball in position A, since the condition P P P where P, is the atmospheric pressure must prevail, in order to maintain the position of the ball.

When a negative pulse of predetermined amplitude and duration is applied to input lead 37, it cannot be trans mitted to P through the. restriction 32, because P /P is critical at the beginning and even more so after the start of the signal pulse. It will however definitely be transmitted to P through lower restriction orifice 33 because P /P is subcritieal and remains subcritieal even after the pulse'has been initiated.

As a result a drop in pressure P occurs in the lower portion of cavity 11; P cannot be reduced immediately because of the small clearance between the ball and the interior of the cavity ll.

The equilibrium conditions expressed by the Equation 1 are disturbed and the ball is driven from the upper seat 17 to the lower seat 13, shown in FiGURE 2.

Since upper axial connection 14 is 'now open and the lower axial connection 15 closed, Output I from lead 23 senses a pressure drop, and Output II senses a pressure rise. Successive input signals will cause each time a succession of pressure drops and rises in each of the two outputs; a rise in one output Will be accompanied by a drop in the other output.

It is thus apparent that each of the two Outputs I and II can be used separately to actuate a binary device, as for example, a binary counter.

It will be apparent to those skilled in the art, that the present invention is not limited to the specific details described above and shown in the drawings, and that various modifications are possible in carrying out the features of the invention and the operation and the method of support, mounting, adjustment, and utilization thereof, withoutdeparting from the spirit and scope of the appended claims.

What I claim is:

1. In combination with a'bistable pneumatic element including a valve member shiftable between two stable, passage-closing positions by means of pressure changes at the respective outlets of the passages controlled by the valve member,

a pneumatic circuit comprising:

a pair of parallel branches having common inlet and outlet portions; respective, identical, fiow restrictions in said branches adapted to produce critical flow under all operating conditions of the circuit; additional, respective, identical flow restrictions in said parallel branches downstream of the firstmentioned flow restrictions adapted selectively to produce critical and subcritical flow depending on operating conditions of the circuit; respective flow connections between said passages and said parallel branches at respective points between the flow restrictions therein; respective output pressure signal connections to said parallel branches at respective locations intermediate the downstream flow restriction and flow connection point of the corresponding passage; and an input pressure signal connection to said common outlet portion.

2. A pneumatic circuit according to claim 1 including a flow restriction in said common outlet portion located 3,168,898 V 6 downstream of said input pressure signal connection and reciprocative movement between limit positions adapted to produce critical fiow under all operating condefined by engagement of the valve member ditions of the circuit. with said valve seats, the cross-section of the 3. A pneumatic circuit comprising, in combination, a valve member being proportioned relative to the bistable-pneumatic element and fiow conduit means for 5 cavity cross-section so as to define a periphconnecting said element between a source of gas under eral clearance space therebetween, said end pressure and regions of lower pressure, walls and sidewalls coacting with said valve said bistable element comprising: member at the limits of reciprocation to enclose enclosure means defining a cavity having end walls respective portions of said cavity adjacent the and sidewalls, said end walls containing respec- 10 end walls, said cavity portions being completely tive passages in communication with said partitioned from the remainder of the cavity excavity; cept for flow communication through said pemeans defining respective, coaxially aligned valve ripheral clearance space; and

seats circumscribing the inner ends of said end means defining respective additional passages in wall passages; said enclosure means continuously open to said a valve member, adapted alternately to seat on cavity portions;

each of said valve seats and close the corresaid fiow conduit means including: sponding passage, conforming in cross-sectional a pair of parallel branches having common inlet contour to said cavity and disposed therein for and outlet portions; reciprocative movement between limit positions respective, identical, flow restrictions in said defined by engagement of the valve member with branches adapted to produce critical flow under said valve seats, the cross-section of the valve all operating conditions of the circuit; member being proportioned relative to the cavity additional, respective, identical flow restrictions in cross-section so as to define a peripheral clearsaid parallel branches downstream of the firstance space therebetween, said end walls and side- 2 mentioned flow restrictions adapted selectively walls coacting with said valve member at the to produce critical and subcritical flow delimits of reciprocation to enclose respective porpending on operating conditions of the circuit; tions of said cavity adjacent the end walls, said an outlet flow restriction in the common outlet cavity portions being completely partitioned portion of said branches adapted to produce from the remainder of the cavity except for flow critical flow under all operating conditions of communication through said peripheral clearthe circuit; ance space; and respective fiow connections between said end wall means defining respective additional passages in passages and said parallel branches at respecsaid enclosure means continuously open to said tive points between the flow restrictions therein; cavity portions; 3

said flow conduit means including: said parallel branches at respective locations inrespective output pressure signal connections to a pair of parallel branches having common inlet and outlet portions;

respective, identical, flow restrictions in said branches adapted to produce critical fiow under all operating conditions of the circuit;

additional, respective, identical flow restrictions in said parallel branches downstream of the firstmentioned flow restrictions adapted selectively to produce critical and subcritical flow depending on operating conditions of the circuit; respective flow connections between said end wall outlet fiow restriction.

6. A pneumatic circuit comprising, in combination, a bistable pneumatic element and flow conduit means for connecting said element between a source of gas under pressure and regions of lower pressure,

said bistable element comprising:

passages and said parallel branches at respective points between the flow restrictions therein; respective output pressure signal connections to enclosure means defining a cylindrical cavity having end walls containing respective coaxial flow passages therethrough;

said parallel branches at respective locations means defining respective, coaxial, inwardly prointermediate the downstream flow restriction and jecting valve seats circumscribing the inner ends flow connection point of the corresponding end of said end wall passages; wall passage; and a spherical valve member disposed within said an input pressure signal connection to said comcavity, with a predetermined small peripheral mon outlet portion. clearance, for reciprocative movement between 4. A pneumatic circuit according to claim 3 including a limit positions defined by closing engagement of flow restriction in said common outlet portion located the valve member with the valve seats, the end downstream of said input pressure signal connection and walls and sidewalls of the cavity coacting with the adapted to produce critical flow under all operating convalve member at said limit positions to enclose ditions of the circuit. respective portions of the cavity, adjacent the 5. A pneumatic circuit comprising, in combination, at end walls, completely partitioned from the rebistable pneumatic element and fiow conduit means for mainder of the cavity except for flow commuconnecting said element between a source of gas under nication through said peripheral clearance space; pressure and regions of lower pressure, and

said bistable element comprising: means defining respective additional passages in enclosure means defining a cavity having end walls said enclosure means continuously open to said and sidewalls, said end walls containing respeccavity portions; tive passages in communication with said cavity; said flow conduit means including: means defining respective, coaxially aligned valve a pair of parallel branches having common inlet seats circumscribing the inner ends of said end and outlet portions; wall passages; respective, identical, flow restrictions in said a valve member, adapted alternately to seat on branches adapted to produce critical flow under each of said valve seats and close the correall operating conditions of the circuit; sponding passage, conforming in cross-sectional additional, respective, identical flow restrictions contour to said cavity and disposed therein for in said parallel branches downstream of the firstmentioned flow restrictions adapted selectively resp ctiv output pressure signal connections to to produce critical and subcritical flow depend- Said Pawne1 bfaflcms at RSPactive locations j on Operating conditions f the circuit; termediate the downstream flow restriction and an outlet flow restriction in the common outlet flow conngction Point of the corresponding end portion of said branches adapted to produce 5 wall passage; and

critical flow under all operating conditions of an Input pressure-.slgnal connection to.sa1d

the circuit; 7 mon outlet port on on the upstream s1de of sa d respective flow connections between said end wall outlet flow restncnon' passages and said parallel branches at re- 10 References Cited in the file of this patent spective points between the flow restrictions Computing wi h Ai M hin Design, June 8, 1961, therein; pa es 24-48 

1. IN COMBINATION WITH A BISTABLE PNEUMATIC ELEMENT INCLUDING A VALVE MEMBER SHIFTABLE BETWEEN TWO STABLE, PASSAGE-CLOSING POSITIONS BY MEANS OF PRESSURE CHANGES AT THE RESPECTIVE OUTLETS OF THE PASSAGES CONTROLLED BY THE VALVE MEMBER, A PNEUMATIC CIRCUIT COMPRISING: A PAIR OF PARALLEL BRANCHES HAVING COMMON INLET AND OUTLET PORTIONS; RESPECTIVE, IDENTICAL, FLOW RESTRICTIONS IN SAID BRANCHES ADAPTED TO PRODUCE CRITICAL FLOW UNDER ALL OPERATING CONDITIONS OF THE CIRCUIT; ADDITIONAL, RESPECTIVE, IDENTICAL FLOW RESTRICTIONS IN SAID PARALLEL BRANCHES DOWNSTREAM OF THE FIRSTMENTIONED FLOW RESTRICTIONS ADAPTED SELECTIVELY TO PRODUCE CRITICAL AND SUBCRITICAL FLOW DEPENDING ON OPERATING CONDITIONS OF THE CIRCUIT; RESPECTIVE FLOW CONNECTIONS BETWEEN SAID PASSAGES AND SAID PARALLEL BRANCHES AT RESPECTIVE POINTS BETWEEN THE FLOW RESTRICTIONS THEREIN; RESPECTIVE OUTPUT PRESSURE SIGNAL CONNECTIONS TO SAID PARALLEL BRANCHES AT RESPECTIVE LOCATIONS INTERMEDIATE THE DOWNSTREAM FLOW RESTRICTION AND FLOW CONNECTION POINT OF THE CORRESPONDING PASSAGE; AND AN INPUT PRESSURE SIGNAL CONNECTION TO SAID COMMON OUTLET PORTION. 